Foot Posture - The Debated Frame of Reference

by MASS4D® Prescription Orthotics May 30, 2016

The correlations between medial arch collapse of the foot and the most common orthopedic diagnoses is well researched.

The term ‘subtalar neutral’ is most often used as the identifier of healthy foot posture and used as an accepted biomechanical reference. However, as clinicians and scientists, we must question if this belief holds true.

The 26 bones and 33 joints of the foot each possess an individual axis. 

With this level of integrated movement, we suggest that no singular axis should be used to describe foot function. The subtalar joint has a total range of motion of only 6 degrees during the stance phase of gait.

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Further, this motion only occurs in supination prior to forefoot contact. This tiny, 6 degrees of external rotation combined with a posterior slide, moves the head of the talus onto the anterior facet which blocks sagittal plane motion between the talus and the calcaneus so that gastrocnemius and soleus contractions can propel the foot forward around the ankle axis.

In considering subtalar neutral position, it describes a singular rotational position around one axis; biomechanical movements in posture, such as those demonstrated in the foot during pronation and supination are complex, coordinated rotational changes around multiple axis. 

Are we best serving our patients by using only one axis and essentially ignoring multiple others?

The Integrated Multi-Axial Theory™ is an alternative biomechanical theory that assesses the foot in a functionally corrected position. 

This theory looks at a foot during mid-stance, with the heel, first and fifth metatarsals all on the ground to see the maximum supination available in closed chain posture. 

This foot presentation has a healthy medial arch, ankle and mid foot with all having proper functional range of motion. If this posture is not present at mid-stance then it is a red flag for biomechanical failure. 

A foot moving within this integrated multi-axial™ position at stance phase has several advantages, such as:

• adequate supination at heel strike
• a forefoot makes full contact on the ground at mid-stance
• the majority of forefoot load is on the first metatarsal joint at heel lift
• the first metatarsal phalange joint is not limited in dorsiflexion.

Foot posture measurements and assessments using the integrated multi-axial principles allow for the inclusion of the complex arthokinetic movement within the foot. 

If we accept that there is an optimal foot posture unique for each individual (however based on the same reference points) then it provides a more accurate frame of reference for treatment and outcome review. 

It is our duty to continue to challenge research and find the theories and methods that will best serve our patients. 

The foot is an amazing appendage with intricate movements and a structural responsibility to support our entire skeletal system. 

The Integrated Multi-Axial Theory™ provides the best opportunity for broad assessment and treatment planning.

Copyright 2016 MASS4D® All rights reserved. 

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